Marshall mcdonald



M. MCDONALD.

FILTER.

No. 381,406. Patented Apr. 17, 1888.

WITNESSES: I- .6 8 INVENTOR- ATTORNEYS.

Fries.

ATENT MARSHALL MCDONALD, OF WASHINGTON, DISTRICT OF COLUMBIA.

FILTER.

SPECIFICATION forming part of Letters Patent No. 381,406, dated April17, 1888.

Application filed November 51, 1887. Serial No. 251,089. (No model.)

To aZZ whom it may concern:

Beit known that I, MansrLiLL MoDoNALD, of \Vashington city, in theDistrict of Columbia, have invented a new and useful Improvement inFilters, of which the following is a specification.

The object of my invention is to provide a filter for household andgeneral use, which shall perfectly eliminate from a portion of the waterall sedimentary matter and microbes held in suspension, and which shallautomatically clean itself, so as to require no attention noradjustment.

My filter does not proceed upon the plan of filtering all the water thatenters its case, but only a portion of it, the balance being used, inconnection witha body of sand, for scouring or cleansing thefiltering-surface, in a manner heretofore employed.

My invention consists in the peculiar construction and arrangement ofthe filter, which I will now proceed to describe with reference to thedrawings, in which Figure 1 is a vertical transverse section throughline 00 x of Fig. 2. Fig. 2 is a side elevation, partly broken away.Figs. 3 and at are respectively a top and side view of one of thefilteringplatcs. Fig. 5 is a longitudinal section of the filtering-platethrough line y y of Fig. 3, and Fig. (5 is a transverse section throughline 2 .c of Fig. l.

Referring to Figs. 1 and 2, A B represent the outer case,which maybe ofcast-iron, made in two flanged sections bolted together at c.

I is the inIetpipe, which, by a number of short sections or thimbles, O,communicates with the bottom of the case.

E are the outlet-pipes for unfiltered water, of which there are two, oneon each side, and which have short pipeconnections c with the top B ofthe filter-case in the same plane as the inlet-pipes 0 below.

R is a reservoir for the filtered water, which is mounted upon the topsection, B, of the case. Within the lower section, A, of the case isarranged a series of filtering-plates, F. (See Figs. 3 to 6.) Theoutline of these plates is made to correspond with the crosssection ofthe case, and there may be any number of them placed in the case,according to the size of the latter. As shown in Fig. 2, there arethree.

These plates (see Figs. 3 to 6) are made of porous earthenware, and areprovided with a series of longitudinal channel-ways,a, in them, all ofwhich communicate with an outlet, b, at the top. On the sides of theseplates are formed wings or flanges P P, which are set at a reverseinclination to each other, so as to form a chambered space between them,large at the bottom and tapering to asmaller width at the top, andwhereby a tapering chamber or space is also formed between these wingsand the sides of the case, as in Fig. 1, but of a reverse taper-i. 0.,large at the top and small at the bottom. These wings or flanges alsoform abutments that hold the filteringplates spaced the proper distancefrom each other, as shown in Fig. 2. The outlet 1) of eachfilteringplate is connected by a short tube, 1 ,With the reservoir B forfiltered water above, the tubes being closely fitted by means of elasticwashers of soft rubber.

The operation of my filter is as follows: The filtering-plates all beingin place in the lower section of the case,clean sharp sand is filled inaround the same up to the level of the top of the filteriugplates orthereabout, as shown in Fig. 1. \Vater under pressure being now admittedthrough inlct-pipe I,. it passes up through the sand in the centralchambers between the wings P P, making a gradual boiling motion of thesand, which, passing up said chamber into a continually-narrowing space,produces an abrasion against the filteringplates that scours theirsurfaces and dislodges therefrom all adhering matter. This sand risesabove the wings PP and is gradually deposited in the hopper-shapedspaces between the wings P P and the sides of the case,where it settlesand moves gradually to the bottom again,and as it descends to the bottomthrough the contracting side chambers it again scours and cleans theplates. The inflowing currents of water from I, it will be seen, thusproduce a gradual circulation of the sand, the central column graduallyrising and the side columns gradually descending from the cutting actionof the currents at the base of said columns. The unfiltered water passesout through the pipes E E at the top, and to prevent the sand from beingcarried with it the discharge of the water is divided and distributed tothe two pipes E E,so that the water in the space above the sand is in acomparatively quiescent state that permits the sand raised from thecentral chambers to remain for a moment in suspension, and then quietlysettles in the side chambers,down which the columns move for arepetition of the same action. As the water in the filter-case is undera pressure, it will be seen that a portion of the water will filterthrough the constantly cleaned and scoured surfaces of the plates F,and,finding its way to the channel-ways a within,is perfectly filteredand rises through the pipes 12 into the reservoir R for filtered water,where it may be drawn from time to time. To stimulate or quicken thebody of water in reservoir R in drawing the same at the stop-cock s, anaircushion may be formed in the top of reservoir R, as shown in dottedlines, Fig. 1, or a'standpipe, 8, or elevated distributing-pipes withoutan air-chamber,would serve the same purpose.

This filteris designed to have itsoutlet-pipes E E connected with theoutlet-cocks of the house, so that every time Water is drawn for anypurpose not requiring filtered water this action will serve to cleansethe filter. It will therefore be seen from the foregoing that thisfilter constantly cleanses itself without attention with a portion ofthe water which passes through it, and filters another portion so as toalways give a supply of clean filtered water.

To prevent the sand from settling into the inlet-pipe I,a suitable capor valve,0,is placed above the same.

In defining my invention with greater clearness I would state that I amaware that a body of sand has been agitated in a filter against thefiltering-surfaces by the force of the inflowing water; but said sandhad as a body no progressive movement or circulation, but was onlyagitated haphazard after the manner of asand in the-bottom of a spring.My invention is distinctive in that there. is a continuous progressivemovement of the-entire body of sand in the same direction, first risingto the top and then settling in columns from gravity. It cleans by anabrasivesliding action the filtersurface and positively and surely takesaway the adhering matter and holds it until thebottom of the column isreached,where the action of the current cuts the lower portion of thecolumn, washes out the sedimentary matter, and carries it off to thetop, while the clean sand is again deposited in columns to act bygravity again.

I do not confine myself to the particular construction of filter forcarrying out this part of my invention, but may vary the constructionwithout departing from this fundamental and distinctive feature.

Having thus described my invention,what I claim as new. is

1. A filter consisting of the combination of in one or more of theothers with a'progressive circulation in the same direction. as setforth.

2. A filter having beside its filtering-faces an upwardly-convergingchannel for a rising column of sand, and a downwardly-converging chamberfor a descending column of sand in open communication at both top andbottom, in combination with an inlet-pipelocated below the channel forthe ascending column,and an outlet-pipe located above the channel forthe descending column, substantially as and for the purpose described.

3. The filtering-plates F, made of porous earthenware,with channel-waysa in the same, and flanges P P on the sides thereof, substantially asand for the purpose described.

4. The combination of case A B, with inletpipe I and outlets E'E, thechanneled filteringplates F,with wings P P, the reservoir R, and pipe1), connecting said reservoir with the filtering-plates, substantiallyas and for the purpose described. I

MARSHALL MCDONALD.

